zen trace analysis support (#945)

Integrates the **tourist** trace analysis library and builds a full `zen trace` command suite for working with Unreal Engine `.utrace` files.

### Trace analysis library (`thirdparty/tourist/`)
- Adds the tourist library as a third-party dependency with three modules: **foundation** (platform primitives, memory, scheduling), **trace** (UE Trace protocol decoding), and **analysis** (event dispatching and analyzer framework).
- Cross-platform support for Windows, Linux, and macOS.

### `zen trace` CLI commands (`src/zen/cmds/`, `src/zen/trace/`)
- **`zen trace analyze`** — Summarize a `.utrace` file: session metadata, thread inventory, command line + build configuration, CPU profiling scopes, timing, event rates, log messages, and (with symbols) memory allocation metrics including live-allocs dumps, callstack-keyed aggregation, and allocation churn. Optional HTML output for memory reports.
- **`zen trace inspect`** — Dump the event schema (declared types, fields, sizes) from a trace file.
- **`zen trace trim`** — Extract a time-window from a trace into a new `.utrace` file.
- **`zen trace serve`** — Launch a local HTTP server hosting an interactive trace viewer; opens in the default browser.

### Symbolication (`src/zen/trace/symbol_resolver.*`, `thirdparty/raw_pdb/`)
- Pluggable resolver with multiple backends: `pdb` (in-tree raw_pdb), `dbghelp` (Windows), `llvm-symbolizer` (all platforms), `atos` (macOS). An `auto` backend picks the best available tool per platform.
- Microsoft Symbol Server support: downloads PDBs on demand using a redirect-aware HTTP client.
- Local PDB cache keyed by image GUID preserves symbols across binary recompilation.
- Callstack trimming heuristic strips UE internal noise from reports.
- Binary analysis cache (`.ucache_z`) avoids re-resolving the same trace.

### Interactive trace viewer (`src/zen/frontend/html/`, `src/zen/trace/trace_viewer_service.*`)
- Timeline: scope-level detail, horizontal zoom/pan, vertical scrolling, viewport-driven loading with pre-computed LOD for responsive navigation of large traces.
- Thread grouping (collapsible sidebar sections) synthesized from name suffixes, natural sort order, visual distinction between lane threads and OS threads.
- Bookmark and region annotations; region categories with per-category toggles; bookmark marker toggle in the toolbar.
- Filterable Logs tab showing captured `UE_LOG` output.
- Stats tab with per-scope aggregate statistics.
- Memory tab with interactive allocation analysis and an allocation size histogram.
- CsvProfiler event parsing and chart UI.

### Other in-branch supporting changes
- **Cross-platform browser launcher** (`browser_launcher.{h,cpp}`) used by `trace serve`.
- **`ReciprocalU64`** fast 64-bit integer division (zencore/intmath) for trace analyzers.
- **`parallelsort`** cross-platform parallel sort helper (zenutil).
- Frontend zip build rule so the viewer's HTML assets are bundled into `zen.exe`.
- `/Zo` flag for better optimized debug info on Windows release builds.
- `trace-tests.cpp` in the `zen-test` harness (harness itself landed on main via #985).

1 files changed, 198 insertions, 0 deletions

diff --git a/thirdparty/raw_pdb/src/Examples/ExampleIPI.cpp b/thirdparty/raw_pdb/src/Examples/ExampleIPI.cpp
new file mode 100644
index 000000000..5286689e9
--- /dev/null
+++ b/thirdparty/raw_pdb/src/Examples/ExampleIPI.cpp
@@ -0,0 +1,198 @@
+// Copyright 2011-2022, Molecular Matters GmbH <[email protected]>
+// See LICENSE.txt for licensing details (2-clause BSD License: https://opensource.org/licenses/BSD-2-Clause)
+
+#include "Examples_PCH.h"
+#include "ExampleTimedScope.h"
+#include "ExampleTypeTable.h"
+#include "PDB_RawFile.h"
+#include "PDB_InfoStream.h"
+#include "PDB_IPIStream.h"
+#include "PDB_TPIStream.h"
+
+static std::string GetTypeNameIPI(const TypeTable& typeTable, uint32_t typeIndex)
+{
+	// Defined in ExampleTypes.cpp
+	extern std::string GetTypeName(const TypeTable & typeTable, uint32_t typeIndex);
+
+	std::string typeName = GetTypeName(typeTable, typeIndex);
+
+	// Remove any '%s' substring used to insert a variable/field name.
+	const uint64_t markerPos = typeName.find("%s");
+	if (markerPos != typeName.npos)
+	{
+		typeName.erase(markerPos, 2);
+	}
+
+	return typeName;
+}
+
+void ExampleIPI(const PDB::RawFile& rawPdbFile, const PDB::InfoStream& infoStream, const PDB::TPIStream& tpiStream, const PDB::IPIStream& ipiStream);
+
+void ExampleIPI(const PDB::RawFile& rawPdbFile, const PDB::InfoStream& infoStream, const PDB::TPIStream& tpiStream, const PDB::IPIStream& ipiStream)
+{
+	if (!infoStream.HasIPIStream())
+	{
+		return;
+	}
+
+	TimedScope total("\nRunning example \"IPI\"");
+
+	TimedScope typeTableScope("Create TypeTable");
+	TypeTable typeTable(tpiStream);
+	typeTableScope.Done();
+
+	// prepare names stream for grabbing file paths from lines
+	TimedScope namesScope("Reading names stream");
+	const PDB::NamesStream namesStream = infoStream.CreateNamesStream(rawPdbFile);
+	namesScope.Done();
+
+	const uint32_t firstTypeIndex = ipiStream.GetFirstTypeIndex();
+
+	PDB::ArrayView<const PDB::CodeView::IPI::Record*> records = ipiStream.GetTypeRecords();
+
+	std::vector<const char*> strings;
+
+	strings.resize(records.GetLength(), nullptr);
+
+	size_t index = 0;
+
+	for (const PDB::CodeView::IPI::Record* record : records)
+	{
+		const PDB::CodeView::IPI::RecordHeader& header = record->header;
+
+		if (header.kind == PDB::CodeView::IPI::TypeRecordKind::LF_STRING_ID)
+		{
+			strings[index] = record->data.LF_STRING_ID.name;
+		}
+
+		index++;
+	}
+
+	uint32_t identifier = firstTypeIndex;
+
+	std::string typeName, parentTypeName;
+
+	printf("\n --- IPI Records ---\n\n");
+
+	for(const PDB::CodeView::IPI::Record* record : records)
+	{
+		const PDB::CodeView::IPI::RecordHeader& header = record->header;
+
+		if (header.kind == PDB::CodeView::IPI::TypeRecordKind::LF_FUNC_ID)
+		{ 
+			typeName = GetTypeNameIPI(typeTable, record->data.LF_FUNC_ID.typeIndex);
+
+			printf("Kind: 'LF_FUNC_ID' Size: %i ID: %u\n", header.size, identifier);
+			printf(" Scope ID: %u\n Type: '%s'\n Name: '%s'\n\n", 
+				record->data.LF_FUNC_ID.scopeId, 
+				typeName.c_str(), 
+				record->data.LF_FUNC_ID.name);
+
+		}
+		else if (header.kind == PDB::CodeView::IPI::TypeRecordKind::LF_MFUNC_ID)
+		{
+			typeName = GetTypeNameIPI(typeTable, record->data.LF_MFUNC_ID.typeIndex);
+			parentTypeName = GetTypeNameIPI(typeTable, record->data.LF_MFUNC_ID.parentTypeIndex);
+
+			printf("Kind: 'LF_MFUNC_ID' Size: %i ID: %u\n", header.size, identifier);
+			printf(" Parent Type: '%s'\n Type: '%s'\n Name: '%s'\n\n",
+				parentTypeName.c_str(),
+				typeName.c_str(),
+				record->data.LF_MFUNC_ID.name);
+
+		}
+		else if (header.kind == PDB::CodeView::IPI::TypeRecordKind::LF_BUILDINFO)
+		{
+			printf("Kind: 'LF_BUILDINFO' Size: %u ID: %u\n", header.size, identifier);
+
+			if (record->data.LF_BUILDINFO.count == 0)
+			{
+				continue;
+			}
+
+			printf("Strings: '%s'", strings[record->data.LF_BUILDINFO.typeIndices[0] - firstTypeIndex]);
+
+			for (uint32_t i = 1, size = record->data.LF_BUILDINFO.count; i < size; ++i)
+			{
+				const uint32_t stringIndex = record->data.LF_BUILDINFO.typeIndices[i];
+
+				if (stringIndex == 0)
+				{
+					printf(", ''");
+				}
+				else
+				{
+					printf(", '%s'", strings[stringIndex - firstTypeIndex]);
+				}
+			}
+
+			printf("\n\n");
+		}
+		else if (header.kind == PDB::CodeView::IPI::TypeRecordKind::LF_SUBSTR_LIST)
+		{
+			printf("Kind: 'LF_SUBSTR_LIST' Size: %u ID: %u\n", header.size, identifier);
+
+			if (record->data.LF_SUBSTR_LIST.count == 0)
+			{
+				continue;
+			}
+
+			printf(" Strings: '%s'", strings[record->data.LF_SUBSTR_LIST.typeIndices[0] - firstTypeIndex]);
+
+			for (uint32_t i = 1, size = record->data.LF_SUBSTR_LIST.count; i < size; ++i)
+			{
+				const uint32_t stringIndex = record->data.LF_SUBSTR_LIST.typeIndices[i];
+
+				if (stringIndex == 0)
+				{
+					printf(", ''");
+				}
+				else
+				{
+					printf(", '%s'", strings[stringIndex - firstTypeIndex]);
+				}
+			}
+
+			printf("\n\n");
+		}
+		else if (header.kind == PDB::CodeView::IPI::TypeRecordKind::LF_STRING_ID)
+		{
+			printf("Kind: 'LF_STRING_ID' Size: %u ID: %u\n", header.size, identifier);
+
+			printf(" Substring ID: %u\n Name: '%s'\n\n", record->data.LF_STRING_ID.id, record->data.LF_STRING_ID.name);
+		}
+		else if (header.kind == PDB::CodeView::IPI::TypeRecordKind::LF_UDT_SRC_LINE)
+		{
+			typeName = GetTypeNameIPI(typeTable, record->data.LF_UDT_SRC_LINE.typeIndex);
+
+			const uint32_t stringIndex = record->data.LF_UDT_SRC_LINE.stringIndex;
+
+			printf("Kind: 'LF_UDT_SRC_LINE' Size: %u ID: %u\n", header.size, identifier);
+
+			printf(" Type: '%s'\n Source Path: %s\n Line: %u\n\n", 
+				typeName.c_str(),
+				strings[stringIndex - firstTypeIndex],
+				record->data.LF_UDT_SRC_LINE.line);
+		}
+		else if (header.kind == PDB::CodeView::IPI::TypeRecordKind::LF_UDT_MOD_SRC_LINE)
+		{
+			typeName = GetTypeNameIPI(typeTable, record->data.LF_UDT_MOD_SRC_LINE.typeIndex);
+
+			const char* string = namesStream.GetFilename(record->data.LF_UDT_MOD_SRC_LINE.stringIndex);
+
+			printf("Kind: 'LF_UDT_SRC_LINE' Size: %u ID: %u\n", header.size, identifier);
+
+			printf(" Type: '%s'\n Source Path: %s\n Line: %u\n Module Index: %u\n\n",
+				typeName.c_str(),
+				string,
+				record->data.LF_UDT_MOD_SRC_LINE.line,
+				record->data.LF_UDT_MOD_SRC_LINE.moduleIndex);
+		}
+		else
+		{
+			printf("Kind: 0x%X Size: %u ID: %u\n\n", static_cast<uint32_t>(header.kind), header.size, identifier);
+		}
+
+		identifier++;
+	}
+}